Sandy and storm surge pose 'worst case scenario'

Seth Borenstein, AP Science Writer

Monday, October 29, 2012

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KENSINGTON, Md. (AP) — The projected storm surge from Hurricane Sandy is a “worst case scenario” with devastating waves and tides predicted for the highly populated New York City metro area, government forecasters said Sunday.

The more they observe it, the more the experts worry about the water — which usually kills and does more damage than winds in hurricanes.

In this case, seas will be amped up by giant waves and full-moon-powered high tides. That will combine with drenching rains, triggering inland flooding as the hurricane merges with a winter storm system that will worsen it and hold it in place for days.

Louis Uccellini, environmental prediction chief for the National Oceanic and Atmospheric Administration, told The Associated Press that given Sandy’s due east-to-west track into New Jersey, that puts the worst of the storm surge just north in New York City, Long Island and northern New Jersey. “Yes, this is the worst case scenario,” he said.

In a measurement of pure kinetic energy, NOAA’s hurricane research division on Sunday ranked the surge and wave “destruction potential” for Sandy — just the hurricane, not the hybrid storm it will eventually become — at 5.8 on a 0 to 6 scale. The damage expected from winds will be far less, experts said. Weather Underground meteorologist Jeff Masters says that surge destruction potential number is a record and it’s due to the storm’s massive size.

“You have a lot of wind acting over a long distance of water for hundreds of miles” and that piles the storm surge up when it finally comes ashore, Masters said. Even though it doesn’t pack much power in maximum wind speed, the tremendous size of Sandy — more than 1,000 miles across with tropical storm force winds — adds to the pummelling power when it comes ashore, he said.

The storm surge energy numbers are bigger than the deadly 2005 Hurricane Katrina, but that can be misleading. Katrina’s destruction was concentrated in a small area, making it much worse, Masters said. Sandy’s storm surge energy is spread over a wider area. Also, Katrina hit a city that is below sea level and had problems with levees.

National Hurricane Center Director Rick Knabb said Hurricane Sandy’s size means some coastal parts of New York and New Jersey may see water rise from 6 to 11 feet from surge and waves. The rest of the coast north of Virginia can expect 4 to 8 feet of surge.

The full moon today will add 2 to 3 inches to the storm surge in New York, Masters said.

“If the forecasts hold true in terms of the amount of rainfall and the amount of coastal flooding, that’s going to be what drives up the losses and that’s what’s going to hurt,” said Susan Cutter, director of the hazards and vulnerability research institute at the University of South Carolina.

Cutter said she worries about coastal infrastructure, especially the New York subways, which were shutting down Sunday night.

Klaus Jacob, a Columbia University researcher who has advised the city on coastal risks, said, “We have to prepare to the extent we can, but I’m afraid that from a subway point of view, I think it’s beyond sheer preparations. I do not think that there’s enough emergency measures that will help prevent the subway from flooding.”

U.S. stock markets are closed and are likely to remain closed Tuesday. The last time the New York Stock Exchange had an unplanned closing was after the terrorist attacks of September 2001.

A spokesman for the exchange said an official announcement would be made later today about whether the closures would extend into Tuesday, but Duncan Niederauer, the chief executive of the exchange’s parent company, NYSE Euronext, told CNBC this morning that it was “hard to imagine” that the exchange would open on Tuesday.

If that happens, it would be it would be the first time since 1888 that weather caused a two-day shutdown of the exchange. The cause then was a blizzard that left drifts as high as 40 feet in the streets of New York City.